β -Caryophyllene, a Natural Sesquiterpene, Attenuates Neuropathic Pain and Depressive-Like Behavior in Experimental Diabetic Mice

Neuropathic pain (NP) is associated with chronic hyperglycemia and emotional disorders such as depression in diabetic patients, complicating the course of treatment. Drugs currently used to treat NP have undesirable side effects, so research on other natural sources has been required. β-caryophyllene (BCP), a natural sesquiterpene found in some food condiments and considered an agonist to cannabinoid receptor type 2, could have potential therapeutic effects to treat conditions such as NP and emotional disorders. For this reason, we assessed whether BCP modulates nociception, anxiety, and depressive-like behavior in streptozotocin (STZ)-induced experimental diabetic BALB/c female mice. BCP was orally chronic administrated (10 mg/kg/60 μL). Pain developed with STZ was evaluated with von Frey filament test, SMALGO^®, and hot plate test. Anxiety and depression-like behavior were assessed by marbles test, forced swim test, and tail suspension test. BCP significantly reduced glycemia in experimental diabetic mice. The pain was also mitigated by BCP administration. Depression-like behavior assessed with tail suspension test was attenuated with orally chronic BCP administration. Substance P and cytokines such as interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), and interleukin-6 (IL-6) were also attenuated with BCP administration. NP was positively correlated with substance P and IL-6 and IL-1β release. Our data using an orally chronic BCP administration in the STZ challenged mice to suggest that glycemia, diabetes-related NP, and depressive-like behavior could be prevented/reduced by dietary BCP.